I agree with a lot of the points made. I'm a big dude, and I make bikes mostly with 4130. I have a long list of reasons, and I did essentially search for cases that would support my prejudice, but if you go this route, you are in good company. Somewhere I kept a list of recipes for clydes, though I am not sure I have it on this computer.
You may want to break out your analysis a little. For instance do you want a fancy bike with say 953. I'm sure if you asked someone could it, or some other specialty, be done, it would be possible. But if you are asking for options to go to plain tubing, they exist also. At the low end of custom plain/plane tubing won't save anything, though I guess it does at the high end, but I actually prefer it. Putting butts in tubing only answers a specific set of questions not all questions.
My own experience, as opposed, slightly, to my research, is that the heavy person can actually ride most lighter bikes. When I was 22 and stronger I weighed 195. When I took up serious cycling again at 45 for rehab from an injury, I was 270, riding a loaded bike with probably 80 pounds on it. I still owned some of my earlier bikes, and the one bike I bought was just a standard touring frame. I think weight imposes limits even on an otherwise fit hefty dude that compensate a lot for carrying that weight. Dead weight falling from on high may defeat a frame at higher magnitudes, but just heavy weight in the saddle is not always decisive. Meaning, if you are thinking of riding on the road, or smooth trail without a penchant for hopping off things, etc... you can get away with most sturdy looking stock bikes.